Nutrition and Cancer Risk: Part 1
No Proven “Anti-Cancer” Diet, But Clear Principles
Nutrition and cancer is a massive topic—one that could fill an entire Substack (and then some). It’s also one of the most common and misunderstood areas in cancer wellness. With so much conflicting information out there, it’s easy to feel overwhelmed.
In this post, we’re tackling some of the biggest concepts first. From sugar and inflammation to gut health and obesity, we’ll explore how nutrition impacts cancer risk and overall wellness. This isn’t about quick fixes or fad diets—it’s about understanding the science and focusing on practical, sustainable changes you can make today.
The more I’ve explored the science of nutrition and cancer, the more I’ve come to appreciate both its potential and its complexities. While plenty of evidence shows how diet impacts cancer risk, myths and oversimplifications often dominate the internet. The idea of a single "superfood" curing cancer or one particular food causing it is appealing—but simply not true.
Cancer risk is shaped by many factors, including genetics, overall diet patterns, lifestyle, and environmental influences. No single food is solely responsible for causing or curing cancer. That’s why I emphasize small, consistent dietary changes with my patients. These manageable strategies can have a meaningful impact over time—and they’re exactly what we’ll explore here.
Top 5 Questions I Hear from Cancer Patients:
Does intermittent fasting help with cancer prevention or treatment?
Can an “alkaline” diet reduce cancer risk or help treat it?
Is juicing an effective way to support my immune system during or after treatment?
Does reducing or eliminating sugar lower cancer risk or improve outcomes?
Are diet sodas, red dyes, or other additives increasing my risk?
Other Common Questions:
Diet and Food Choices
Does eating organic food reduce cancer risk?
Should I avoid all red meat or processed meats entirely?
Are soy products safe for people with hormone-sensitive cancers?
Does dairy increase my cancer risk?
Supplements and Additives
Are there specific foods or supplements that can boost my immune system?
Lifestyle Factors
Can alcohol increase my cancer risk or affect treatment outcomes?
Are there specific foods I should focus on to help prevent recurrence?
My focus in this post is on the big-picture principles of a diet that can help reduce cancer risk—practical, evidence-based guidance that you can use right away. We will try to tackle of few of the questions above. In future posts, we’ll dig deeper into specific topics, exploring the science behind the trends and questions I hear most often. I would also love to hear from subscribers what topics you feel are important to discuss. If I missed something big, feel free to reach out!
What’s Really Driving Cancer Risk?
The link between nutrition and cancer is complex, and the science can feel overwhelming. What we do know is that diet significantly influences biological pathways that drive cancer development. Four key factors stand out:
Obesity: Excess body fat creates hormonal imbalances and promotes chronic inflammation, both of which can fuel cancer.
Chronic Inflammation: Ongoing low-grade inflammation damages tissues and DNA, providing fertile ground for cancer cells to thrive.
Insulin Resistance: Poor blood sugar regulation raises insulin and IGF-1 levels, stimulating cancer cell growth.
Gut Dysbiosis: Imbalances in gut bacteria weaken the immune system and contribute to inflammation, increasing cancer risk.
These factors often work together in a harmful cycle, which is why addressing them holistically through diet and lifestyle is so important.
1. Obesity: A Major but Multifaceted Risk Factor
Obesity is one of the most significant contributors to cancer risk, associated with at least 13 types of cancer, including breast, colorectal, pancreatic, and endometrial cancers.1
Here’s how excess body fat drives cancer risk:
Hormonal Changes: Fat tissue produces hormones like estrogen, which can fuel hormone-sensitive cancers such as breast and endometrial cancer.
Chronic Inflammation: Fat cells release pro-inflammatory molecules (like TNF-α and IL-6) that damage DNA and promote tumor growth.
Insulin and IGF-1 Dysregulation: Obesity increases insulin resistance, leading to higher levels of insulin and IGF-1, both of which stimulate cancer cell growth and survival.
While obesity is a significant risk factor, not all obese individuals have the same cancer risk. Genetics, lifestyle, and metabolic health also play crucial roles, reminding us that weight alone doesn’t tell the whole story.
2. Chronic Inflammation: The Silent Driver
Inflammation is a normal immune response to injury or infection, but when it becomes chronic, it can drive cancer development. Chronic inflammation damages tissues and DNA, creating an environment where cancer cells can thrive.2
Diet and Inflammation:
Diets high in processed foods, added sugars, and unhealthy fats exacerbate inflammation by increasing levels of pro-inflammatory markers
Conversely, diets rich in fruits, vegetables, whole grains, and omega-3 fatty acids can lower inflammation. Compounds like polyphenols (found in berries and green tea) and curcumin (from turmeric) have anti-inflammatory effects that may reduce cancer risk.
Why It Matters: Chronic inflammation doesn’t just affect obese individuals—it can occur in people of any body weight due to poor diet, stress, or other environmental factors. Addressing inflammation through diet is a key strategy for cancer prevention.
3. Insulin Resistance: A Hidden Culprit
Insulin resistance occurs when cells in the body become less responsive to insulin, leading to higher circulating insulin levels. Over time, this condition can contribute to cancer in several ways:
Hyperinsulinemia: Elevated insulin levels promote cell proliferation and reduce apoptosis (cancer cell death), creating an environment conducive to tumor growth.
IGF-1 Activation: Insulin resistance often leads to increased levels of IGF-1, a growth factor that has been directly linked to several cancers, including colorectal, prostate, and breast cancers.
Metabolic Dysfunction: Insulin resistance is also associated with other cancer-promoting conditions, such as oxidative stress and mitochondrial dysfunction.
Dietary Connections: Diets high in refined carbohydrates, added sugars, and processed foods exacerbate insulin resistance. On the other hand, high-fiber diets and foods with a low glycemic index (like legumes, non-starchy vegetables, and whole grains) improve insulin sensitivity.
4. Gut Dysbiosis: Weakened natural defense system
This is the one I find the most fascinating. Our gut bacteria (microbiome) plays a vital role in overall health, including cancer prevention. An imbalance in gut bacteria (dysbiosis) can lead to chronic inflammation, weaken the immune system, and produce harmful substances that increase cancer risk.3 Maintaining a healthy microbiome is an important part of reducing the risk of cancer and supporting long-term wellness.
Boosts Immune Function: A healthy microbiome supports the immune system, enhancing its ability to identify and destroy cancer cells before they grow or spread.
Reduces Inflammation: Balanced gut bacteria help lower chronic inflammation, a key factor that can contribute to DNA damage and cancer development.
Produces Protective Compounds: Beneficial bacteria generate short-chain fatty acids (like butyrate) and other metabolites that strengthen the gut barrier, promote cell health, and protect against harmful toxins.
No Proven “Anti-Cancer” Diet, But Clear Principles
Research has consistently shown that certain dietary patterns reduce risk by addressing these underlying mechanisms:
Mediterranean Diet: Emphasizing whole foods, healthy fats (like olive oil), and a variety of plant-based foods, this diet is associated with lower inflammation and improved insulin sensitivity.4
Plant-Based Diets: Rich in fiber, antioxidants, and phytochemicals, plant-based diets support gut health, reduce inflammation, and regulate hormones.
Low Glycemic Index Diets: Diets that avoid rapid blood sugar spikes help stabilize insulin levels, reducing a key cancer risk factor.
High-Fiber Diets: High-fiber diets are especially effective for reducing colorectal cancer risk, but their benefits extend to other cancers as well. Fiber improves gut health by promoting beneficial bacteria, reduces inflammation, and regulates hormones. A recent meta-analysis found that individuals who consume 25–30 grams of fiber daily experience a 20% reduction in colorectal cancer risk.5
It’s Not Just Obesity
Importantly, many of these cancer-promoting mechanisms—chronic inflammation, insulin resistance, and hormonal dysregulation—can occur independently of obesity. This explains why maintaining a healthy weight is important, but not the whole story. A lean person with poor dietary habits, high stress, or other risk factors can still experience these pro-cancer conditions.
The goal isn’t just weight loss—it’s metabolic health. By focusing on anti-inflammatory, nutrient-dense foods and improving insulin sensitivity, we can address the root causes of diet-related cancer risk, regardless of body size.
The Practical Takeaways
Focus on nutrient-dense meals: Build your plate with vegetables, lean proteins, whole grains, and healthy fats.
Avoid processed foods: Skip sugary snacks, fast food, and refined carbs that add empty calories.
Be mindful of portions: avoiding oversized servings can help with calorie control.
Snack smart: Replace calorie-dense snacks like chips with fruit, nuts, or yogurt.
Reduce Inflammation with Anti-Inflammatory Foods
Use healthy fats: Incorporate extra virgin olive oil, nuts, seeds, and fatty fish like salmon, rich in omega-3s.
Eat the rainbow: Include a variety of colorful fruits and vegetables for antioxidants and phytonutrients.
Spice it up: Add turmeric, ginger, and garlic to meals for their anti-inflammatory properties
Limit inflammatory foods: Cut back on processed meats, fried foods, and added sugars.
Improve Insulin Sensitivity with Low-Glycemic Foods
Prioritize whole grains: Choose options like quinoa, oats, and brown rice over white bread or pasta.
Limit sugary drinks: Replace sodas and juices with water or unsweetened herbal tea.
Pair carbs with protein or fat: Combining foods (e.g., an apple with almond butter) can help stabilize blood sugar.
Watch added sugars: Read labels and aim to minimize sugar in processed foods.
Support a Healthy Gut Microbiome
Eat more fiber: Include plenty of fruits, vegetables, legumes, and whole grains to nourish good gut bacteria.
Incorporate fermented foods: Add yogurt, kefir, kimchi, or sauerkraut to your diet to boost the beneficial bacteria in your gut
Limit artificial additives: Reduce consumption of artificial sweeteners and heavily processed foods.
Probiotics are not a substitute for a fiber-rich diet, I do not routinely recommend them
Keep It Simple: Practical Tips
Meal prep and plan ahead: Having healthy options ready can prevent impulse eating.
Make small changes over time: Start by adding one or two healthy habits each week.
Stick to the basics: Focus on whole, minimally processed foods
Practice consistency, not perfection: Long-term habits matter more than occasional indulgences.
Q and A:
Does intermittent fasting help with cancer prevention or treatment?
Intermittent fasting is an exciting area of research, showing real promise in preclinical studies for reducing cancer risk and even enhancing the effectiveness of certain cancer treatments. In animal models, fasting has been shown to reduce inflammation, improve insulin sensitivity, and amplify the impact of therapies. Early human studies are encouraging, suggesting that time-restricted eating can support weight management and metabolic health—key factors linked to a lower cancer risk. I would love to see more clinical trials in cancer patients to better understand its potential effects. As research advances, we’re likely to learn even more about its role in cancer prevention and treatment. Stay tuned for a deeper dive into the science and practical applications of intermittent fasting in upcoming posts!
Is there any legitimacy to eating an “alkaline” diet?
The science behind alkaline diets is based on the misconception that dietary choices can significantly alter the body’s systemic pH to prevent or treat cancer. In reality, the body tightly regulates blood pH (7.35–7.45) through buffering systems in the kidneys and lungs, and diet has minimal impact on this balance. While alkaline-promoting foods like fruits, vegetables, and nuts are linked to reduced cancer risk, this benefit comes from their high levels of fiber, antioxidants, and anti-inflammatory compounds—not their pH effects. Similarly, acidic foods like red and processed meats are associated with increased cancer risk due to other factors, such as carcinogenic compounds and low fiber content. Although the diet’s premise is flawed, its focus on whole, plant-based foods aligns with evidence-based recommendations for reducing cancer risk
Does juicing have any beneficial impact on cancer?
While juicing might seem like a quick way to boost fruit and vegetable intake, I generally recommend avoiding it for a few key reasons. Juicing removes most of the fiber from fruits and vegetables. Fiber is essential for gut health, promoting a healthy microbiome and reducing inflammation—both critical for cancer prevention and overall wellness. Juices, especially those high in fruit content, can cause rapid increases in blood sugar levels. This may lead to spikes in insulin and IGF-1 (insulin-like growth factor), which are thought to potentially influence cancer growth in certain cases. Eating whole fruits and vegetables provides the full nutritional benefit, including fiber, which slows digestion and helps stabilize blood sugar.
When Juicing Might Be Considered
Juicing could be an option if you're struggling to eat enough fruits and vegetables due to poor appetite, difficulty chewing, or swallowing issues. If you choose to juice, focus on low-glycemic vegetables (e.g., spinach, kale, cucumber) with minimal fruit for sweetness. Pair the juice with a source of protein or healthy fat to reduce blood sugar spikes.
I hear sugar feeds cancer, should I reduce or eliminate sugar in my diet?
One of the most common questions patients ask is whether sugar "feeds" cancer. This concern stems from the Warburg effect, where cancer cells preferentially use glycolysis for energy, even in oxygen-rich environments. However, not all sugars affect cancer equally, and recent research has focused on fructose as a potential driver in cancer progression.
A 2024 Nature study investigated the effects of dietary fructose on tumor growth in animal models of melanoma, breast cancer, and cervical cancer. Researchers found that fructose supplementation significantly accelerated tumor growth, even without causing weight gain6
Fructose Metabolism: Unlike glucose, fructose isn't directly metabolized by cancer cells because they lack the enzyme ketohexokinase (KHK). Instead, fructose is processed by the liver and converted into lipids, which cancer cells can use to fuel growth and proliferation.
Tumor Impact: The study demonstrated that these liver-derived lipids provide a metabolic advantage to tumors, helping them grow faster.
High-fructose corn syrup and sugary beverages, common in processed foods, are major sources of fructose and should be minimized. Whole fruits, however, contain natural sugars paired with fiber, vitamins, and antioxidants, making them a healthier option.
While more research is needed to translate these findings into human cancer care, the evidence suggests that reducing added fructose, particularly from processed sources, could be a prudent step for patients concerned about cancer progression or prevention.
Final Takeaways
Nutrition is not a cure-all, but it’s a powerful tool to complement cancer prevention and care. Focus on small, consistent changes: minimize processed and sugary foods, emphasize whole, nutrient-dense options, and maintain a healthy weight.
By understanding the role of diet in cancer, you can take practical steps to support your health and well-being in ways that align with the latest evidence. As always, consult your medical team for personalized advice.
Stay curious, stay healthy, and keep making informed choices!
In upcoming posts, I’ll tackle soy, dairy, organic foods, and more. Have a question you want answered? Let me know—I’d love to include it!
Body Fatness and Cancer — Viewpoint of the IARC Working Group N Engl J Med 2016; 375:794-798
Liu XZ, Pedersen L, Halberg N. Cellular mechanisms linking cancers to obesity. Cell Stress 2021; 5(5):55–72.
Sheflin AM, Whitney AK, Weir TL. Cancer-promoting effects of microbial dysbiosis. Current Oncology Reports 2014; 16(10):406.
Nutrients 2021, 13, 3582
The Lancet, Volume 361, Issue 9368, 1496 - 1501
Thank You for shedding light on the confusion and miss information that is fed to us🌹on other sites‼️
I love bread! What would be a good fiber packed bread? Is it true that gluten is the problem? The fad is sourdough. Any truth to that? I believe in balance and that’s what I try to do. I would like to know when the best time in the day to eat your good carbs, good fats, grains and protein. I don’t believe in fad diets. I just want the truth about food it seems impossible to eat healthy foods unless you grow them or raise the animals yourself. Totally frustrated! Sorry for the ramble…..